Water-absorbing, essentially water-free membrane for reagent substrates and methods of preparing the same

Abstract

In a reagent strip for the dry-chemical detection of a component of an aqueous sample solution comprising a detection reagent in a membrane, the improvement wherein the membrane is an essentially anhydrous, but water-absorbing, membrane for a reagent substrate in an analytical agent for the dry-chemical detection of a component of an aqueous sample solution, comprising at least one hydrophobic film-forming, water insoluble organic polymer in which at least one hydrophilic organic polymer is dispersed as discrete particles. The reagent can be incorporated into the membrane when produced or can later be applied as by impregnation. The membrane performs as well as or better than multi-layer strips.

What is claimed is: 
     
       1. An essentially anhydrous, but water-absorbing, membrane for a reagent substrate in an analytical agent for the dry-chemical detection of a component of an aqueous sample solution, comprising at least one hydrophobic film-forming, water-insoluble organic polymer selected from the group consisting of polyhydrocarbons, polydienes, polyvinyl compounds, polyacrylates or -methacrylates, polycarbonates, polyacetals, polyethers, polyurethanes, phenol resins, polyesters, polysulphones, polyamides and polyimides and organo-soluble polysaccharides in which at least one hydrophilic organic polymer capable of absorbing at least 20% by weight of water is dispersed as discrete particles. 
     
     
       2. The membrane according to claim 1, wherein the at least one hydrophilic polymer is contained in pores of a coherent phase of the membrane made up of the at least one hydrophobic, water-insoluble polymer. 
     
     
       3. The membrane according to claim 1, wherein the weight ratio of the at least one hydrophilic polymer to the at least one hydrophobic polymer is between 10:1 and 1:10. 
     
     
       4. A process for producing an essentially anhydrous, but water-absorbing, membrane for a reagent substrate in an analytical agent for the dry-chemical detection of a component of an aqueous sample solution, comprising mixing a solution of at least one film-forming, hydrophobic water-insoluble organic polymer selected from the group consisting of polyhydrocarbons, polydienes, polyvinyl compounds, polyacrylates or -methacrylates, polycarbonates, polyacetals, polyethers, polyurethanes, phenol resins, polyesters, polysulphones, polyamides and polyimides and organo-soluble polysaccharides with a dispersion of at least one hydrophilic, water-containing organic polymer, wherein the hydrophilic polymer is capable of absorbing at least 20% by weight of water, in an organic solvent to form a mixture, applying the mixture onto a base, and drying. 
     
     
       5. A process for producing an essentially anhydrous, but water-absorbing, membrane for a reagent substrate in an analytical agent for the dry-chemical detection of a component of an aqueous sample solution, comprising dispersing at least one hydrophilic, water-containing, organic polymer, wherein the hydrophilic polymer is capable of absorbing at least 20% by weight of water, in a solution of at least one film-forming, hydrophobic, water-insoluble organic polymer selected from the group consisting of polyhydrocarbons, polydienes, polyvinyl compounds, polyacrylates or -methacrylates, polycarbonates, polyacetals, polyethers, polyurethanes, phenol resins, polyesters, polysulphones, polyamides and polyimides and organo-soluble polysaccharides to form a dispersion, applying the dispersion onto a base, and drying. 
     
     
       6. In a reagent strip for the dry-chemical detection of a component of an aqueous sample solution comprising a detection reagent in a membrane, the improvement wherein the membrane is a membrane according to claim 1. 
     
     
       7. The reagent strip according to claim 6, further including a substrate and at least one additional layer. 
     
     
       8. A process for preparing a reagent strip which includes a detection reagent in a membrane comprising mixing a solution of at least one film-forming, water-insoluble organic polymer selected from the group consisting of polyhydrocarbons, polydienes, polyvinyl compounds, polyacrylates or -methacrylates, polycarbonates, polyacetals, polyethers, polyurethanes, phenol resins, polyesters, polysulphones, polyamides and polyimides and organo-soluble polysaccharides with at least one hydrophilic organic polymer which contains at least 20% by weight of water to form a mixture, with the solution of the at least one water-insoluble polymer or the at least one hydrophilic polymer or both being pre-mixed with a reagent, applying the mixture onto a base, and drying. 
     
     
       9. The process according to claim 8, wherein the reagent is hydrophobic and is pre-dissolved in the solution of the at least one water-insoluble polymer. 
     
     
       10. The process according to claim 8, wherein the at least one hydrophilic polymer is initially present in a water-in-oil emulsion. 
     
     
       11. The process according to claim 10, wherein the reagent is hydrophilic and is present in the aqueous phase of the water-in-oil emulsion. 
     
     
       12. The process according to claim 10, wherein the water-in-oil dispersion of the at least one hydrophilic, water-containing polymer is prepared by inverse emulsion polymerisation of water-soluble monomers.